1. Field of the Invention
The present invention relates to golf equipment and, more specifically, to a diagnostic golf club having the ability to make quantitative measurements of specific mechanical or physical properties of the golf club during a golf swing. Strain gauges are provided on the exterior of the shaft of the golf club and a memory device is provided within the interior containing data descriptive of the measured properties.
2. Description of the Related Art
Various data measuring and collecting devices and methods are used for analyzing a golf club during a golf swing. In a similar manner, the effectiveness of a golf ball impact with the golf club during the golf swing can be measured in terms of initial launch conditions. Such launch conditions include the initial velocity, launch angle, spin rate and spin axis of the golf ball. These launch conditions are determined principally by the velocity of a club head at impact and the loft and angle of a club face relative to the intended trajectory of the golf ball's flight. There are two general methods for analyzing the golf club during a golf swing: visual analysis and quantitative variable analysis.
The method of analyzing a golf club during a golf swing using visual analysis typically is conducted by a golf instructor capable of visually discerning golf swing variables, and suggesting corrections in the golfer's swing to provide improvement. However, not every golfer has ready access to professional golf instruction. The golfer also can diagnose certain swing faults using visual analysis methodology employing one or more cameras to record the golfer's swing and comparing it to a model swing. Using various camera angles and slow motion play back, the actual swing motion can be reviewed and altered in subsequent swings.
On the other hand, quantitative variable analysis employs sensors to directly measure various mechanical or physical properties of the golf club during the swing motion. Sensors, such as strain gauges or accelerometers, typically are attached to the shaft or the golf club head. Data collected from these strain gauges then may be transferred to a signal processor via wires or radio waves, and can be presented in various graphical formats, including graphical and tabular charts. A significant drawback associated with the use of wires in an instrumented golf club is that the wires can be very cumbersome, and can become obtrusive to the golfer when the golfer attempts to swing the golf club. Several different approaches to analyzing a golf club or baseball bat during a baseball or golf swing using quantitative variable analysis are discussed in the patents listed below.
For example, in U.S. Pat. No. 4,759,219, issued to Cobb et al., the specification discloses a baseball bat with a self-contained measuring device and display. A spring potentiometer is used to measure centrifugal force, and an LED or LCD displays the measured force. However, this bat does not contain any data storage capability.
U.S. Pat. No. 5,233,544, issued to Kobayashi, discloses a golf club having multiple sensors, and a cable for transmitting data to a computer for data processing. This arrangement can accommodate up to 5 sensors in a cartridge located in the handle region of the golf club.
U.S. Pat. No. 3,182,508, issued to Varju, discloses the use of a strain gauge in the bottom of a golf club, and a wire for connecting the sensor to a data processing means located separate from the golf club.
U.S. Pat. No. 5,694,340, issued to Kim, discloses the use of multiple sensors for measuring the acceleration of a golf club, and uses either a cable or radio transmissions to transfer data from the sensors to an external data processing means.
U.S. Pat. No. 4,991,850, issued to Wilhelm, discloses the use of a sensor for measuring the applied force of a golf swing. The sensor data can be displayed on a wrist-mounted arrangement or be downloaded to a computer via cable or radio transmission.
U.S. Pat. No. 3,792,863, issued to Evans, discloses the use of multiple sensors, including an accelerometer and strain gauges, to measure torque and flex. Data is transferred from the golf club to a data analysis station via FM radio signals, with each sensor having its own data transfer frequency.
Thus, data transfer to an external memory device is a significant drawback. The cumbersome nature of data transfer via cables or wires affects the motion and feel of a golfer's actual golf swing. In addition, while the use of radio transmissions is preferable to the use of wires or cables emanating from the golf club for transferring data, a transmitter adds excessive weight. The effective range of these wireless instrumented golf clubs is limited by the low power used in such embodiments, and the accuracy of the radio transmitted data is subject to interference or noise from other sources of nearby radio transmissions.
Furthermore, in conventional systems, the receiving equipment typically must be located in close proximity to the radio transmitter disposed in the golf club thereby restricting the flexibility and portability of using such systems. Thus, it is desirable to provide an instrumented golf club that approximates the weight, balance and feel of a golfer's own golf club, in order to ensure that the data collected from the instrumented golf club is applicable to the golfer's actual golf swing. It also may be desirable to provide additional sensors for measuring certain parameters of a golf swing that have previously not been available in instrumented golf clubs. It further may be desirable to provide an efficient means of memory storage within the instrumented golf club to enable internal data capture and storage until the user is ready to download the data for further processing. It further may be desirable to provide data from the instrumented golf club for golf club design.